-- | Operations upon monetary 'Amount's -- -- Converting amounts -- -- >>> convert USD (Amount EUR 23482.34) -- Amount USD 27709.1612 -- -- >>> prettyPrint \$ convert USD (Amount EUR 23482.34) -- "USD 27,709.16" -- -- Comparing amounts -- -- >>> compareAmounts (Amount EUR 1000) (Amount BTC 1) -- LT module Data.Currency.Amounts ( -- * Monetary Amount Amount(..) -- * Converting , toUSD , fromUSD , convert -- * Comparing , compareAmounts , module Data.Currency.Currencies ) where import Data.Currency.Currencies -- | Monetary amounts data Amount c = Amount c Double deriving (Show, Read, Eq) instance (Currency c) => Ord (Amount c) where (Amount _ v1) <= (Amount _ v2) = v1 <= v2 -- | Convert an 'Amount' of an arbitrary currency to 'USD' toUSD :: (Currency c) => Amount c -> Amount USD toUSD (Amount c amount) = Amount USD \$ amount * exchangeUSD c -- | Convert an 'Amount' from 'USD' to a given 'Currency' fromUSD :: (Currency c) => c -> Amount USD -> Amount c fromUSD c (Amount USD amount) = Amount c \$ amount / exchangeUSD c -- | Convert an 'Amount' to a given 'Currency' convert :: (Currency c', Currency c) => c' -> Amount c -> Amount c' convert c' amount = fromUSD c' \$ toUSD amount -- | Compare two 'Amount's of arbitrary currencies compareAmounts :: (Currency c1, Currency c2) => Amount c1 -> Amount c2 -> Ordering compareAmounts a1 a2 = compare (toUSD a1) (toUSD a2)